decode-ways.md

<p>A message containing letters from <code>A-Z</code> is being encoded to numbers using the following mapping:</p>

<pre>
&#39;A&#39; -&gt; 1
&#39;B&#39; -&gt; 2
...
&#39;Z&#39; -&gt; 26
</pre>

<p>Given a <strong>non-empty</strong> string containing only digits, determine the total number of ways to decode it.</p>

<p><strong>Example 1:</strong></p>

<pre>
<strong>Input:</strong> &quot;12&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong>&nbsp;It could be decoded as &quot;AB&quot; (1 2) or &quot;L&quot; (12).
</pre>

<p><strong>Example 2:</strong></p>

<pre>
<strong>Input:</strong> &quot;226&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong>&nbsp;It could be decoded as &quot;BZ&quot; (2 26), &quot;VF&quot; (22 6), or &quot;BBF&quot; (2 2 6).</pre>